What's the best calendar app?

The simple design and functionality are the reasons why I use Google Calendar.

I agree.

Second (third) it. Simple, easy to use and a "no gimmicks" calendar app.

recommend this, as a student using for 2 years. but not sure what your requirment of calendar.

I love this app because of nice UI and well thought UX. It permanently lives in my menu bar, so the calendar is always a click away!

I'm obsessed with Timepage. I admit, I originally got it because I'm a Moleskine brand loyalist and I just jumped on the bandwagon, but I actually turned out to LOVE it. It's just a really brilliantly designed app that keeps getting better with each new update. Color coded / shaded bubbles let you know how busy you are any given day and it's easy to swipe between monthly, weekly, and daily, views to get an accurate and clear view of your schedule.

Came across this one randomly a while back. A bunch of useful views and the "dashboard" view has date, weather, calendar, reminders, and a list of recent and upcoming birthdays if you're into that sort of thing. Also, a *ton* of customizations available in the Settings menu.